Direct potable reuse (DPR) eliminates the environmental buffer stage from IPR, saving time, money, and energy. In some instances, water is delivered directly to taps. This is not as uncommon as you might think as, if you live in one of these states, there’s already recycled sewage in your drinking water.
Drinking water that has recently been sewage swirling down your shower drain, kitchen sink, or toilet bowl may seem quite disgusting. But experts claim it is nothing to be alarmed about, and it might soon arrive in your state or city.
Direct potable reuse, or DPR, is a technique for reusing water in which highly treated sewage water is nearly immediately sent to a drinking water system for distribution to populations. Texas has legalized it, and Arizona has legalized it on a case-by-case basis. Several other states, including California, Colorado, and Florida, are drafting legislation to legalize it as well.
According to experts, the water generated by DPR satisfies government standards for drinking water quality. Additionally, there is a growing effort to encourage acceptance of DPR and other sewage recycling technologies, which were once scorned as “toilet-to-tap” systems.
According to Dan McCurry, a professor of civil and environmental engineering at the University of Southern California, “people need that change in mindset, forgetting where your water came from and focusing more on how clean it is when it’s in front of you.”
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Recycling wastewater can help avoid drinking water shortages
Although the procedure might not sound appealing, DPR might be really helpful if drinking water becomes scarce.
The Colorado River, Lake Mead, and Lake Powell are all critically important natural drinking water supplies that are currently experiencing significant water shortages due to catastrophic drought conditions. Climate change modifies rain and snowmelt patterns, which sends less fresh water (read below) to these sources. Growing populations that want more water will only strain those resources more, making DPR and other similar techniques even more crucial.
DPR has thus far been employed to improve the availability of drinking water in two Texas cities: Big Spring and Wichita Falls. Once state DPR laws are in place, El Paso intends to fall into line, alongside large cities like Los Angeles and San Diego.
Wichita Falls used DPR as an emergency solution to a five-year drought for nearly a year, beginning in July 2014. According to Chris Horgen, the city’s public relations officer, DPR produced 5 million gallons of treated water for the city each day, accounting for one-third of the drinking water provided to taps.
“The state was that close to delivering water bottles to us in that final year,” Horgen says. “That’s what would’ve happened without DPR.”
DPR is not yet operational in El Paso, but the development is underway with the goal of creating a long-term sustainable drinking water supply. According to Christina Montoya, communications and marketing manager at El Paso Water Utilities, broadening the city’s drinking water sources could adequately equip it for severe droughts that endanger natural sources like river water.
“It’s a way to make sure that El Paso will thrive 50 years out from now,” she says. “We can’t just be planning when an emergency happens. We need to be planning all the time for the future.”
Wastewater recycling is nothing new
If you are still concerned about DPR, keep in mind that it is nothing new: recycled sewage may already be in your drinking water. For decades, several cities in the United States have employed a similar system known as indirect potable reuse, or IPR.
In such system, sewage water is processed in a wastewater treatment plant, where it is cleaned to satisfy irrigation standards, or for watering land and crops. The water is then taken to an advanced filtration plant, which, according to McCurry, cleans it even more, often running it through a three-step process that assures it satisfies or even surpasses state and federal drinking water quality standards.
The water is pure at this point. Still, it enters a “environmental buffer,” such as an underground aquifer, where it may spend months or even years filtering. Finally, it is distributed through a drinking water system, according to McCurry.
According to McCurry, DPR eliminates the environmental buffer stage, saving time, money, and energy. In some instances, water is delivered directly to taps. In other circumstances, it is combined with raw water — such as lake water — before being distributed.
As per Patricia Sinicropi, executive director of water industry trade association WateReuse, research demonstrates that modern purification facilities can regularly treat sewage to acceptable drinking levels without the added step of an environmental buffer, which is “really not necessary.”
“That technology can really take any type of water from any source and purify it to the point where the average consumer will have a good experience drinking it,” she says.
How cities are eliminating the ‘yuck factor’
Political hyperbole and media sensationalism created strong public opposition to the notion more than two decades ago, culminating in abandoned projects in cities such as Los Angeles. According to a 2015 survey of 2,000 people in the United States, 13% absolutely refuse to consume recycled sewage, 38% are unsure, and 49% are willing to try it.
As a result, some communities are doing trial runs first.
From 2009 to 2013, San Diego ran a small-scale advanced purification plant that effectively showed that DPR can purify sewage water to safe drinking water standards. That demonstration facility did not transfer any water to taps, so it was totally legal, and it permitted the public to come in and test the water being generated.
In El Paso, a demonstration facility successfully completed its eight-month course in 2016, claims Montoya. Soon after, the city was given permission to build a sizable DPR plant. It will be finished in 2026 and have a daily water production capacity of around 10 million gallons. After seeing the demonstration site, 96% of residents stated they were in favor of the city’s DPR plans.
“We know that the technology can treat wastewater to some of the purest water out there. But it’s that challenge of public acceptance for other parts of the country,” Montoya says. “People just need to understand how important it is.”
Los Angeles has devised a similar strategy to prevent repeating history. After California legalizes DPR and finalizes regulations by the end of 2023, according to Jesus Gonzalez, manager of the recycled water program at the Los Angeles Department of Water and Power, the city will open a demo plant in the city’s centre by late 2024 to represent as a “proof of concept.”
“We want to eliminate the ‘yuck factor’ or people’s negative perception,” he says.
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